Air flotation direction changing roll



p 1957 H. L. SMITH, JR

AIR FLOTATION DIRECTION CHANGING ROLL 2 SheetsSheet 1 Filed June 2, 1966INVENTOR Horace LSm/ih, Jr:

JAMIE}! H, 1967 H. SMITH, JR

AIR FLOTATION DIRECTION CHANGING ROLL 2 SheetsSheec 2 Filed June 2, 19662 haw- 9 a Hi? I? OOOOOOOOOOOO OOOOO W 6 R 4 m M E m 0 V w m a A M C I hm K m -f I LI 1 H M m HUN 4 7 i mm v. d I. //M/ 2 I Q fl M m y 5 1 m m ww W 3 313 452 Am rLorA'rroN nmhciron CHANGING norm Horace L. Smith, J12,Richmond, Va, assignpr to Hupp Corporation, Cleveland, Ohio, acorporation of Virinia g Filed .Iune 2, 1966, Ser. No. 554,842

2 Claims. (6i. 226--97) This application is a continuation-in-part ofapplication No. 289,938, filed June 24, 1963, which is now abandoned.

This invention relates generally to systems for treating continuous webmaterials, and more specifically to novel methods and apparatus of thetype described above including means for changing the direction oftravel of continuous web materials during treatment thereof.

As hereinafter employed, the term treating includes drying, printing,coating, impregnating, dusting, sizing, curing, etc., and is thereforeapplicable, for example, to paper drying, curin. of thermoset resins,coronizing glass fabric, impregnation of materials with plastics, rubberfixation of resin bonded dyes and pigments on web materials, single ormultiple pattern dyeing or otherwise treating and developing specialdesigns such as lace or open area effects in fabrics, tapes, Webs, andthe like.

Printing, coating, impregnation, etc., of web material, including paper,fabrics, thin sheet metal strips, and like materials is commerciallyaccomplished by completely saturating the web material in a bath or, asin the case of sheet metal, simultaneously wetting or coating both sidesby spraying, for example. Subsequently, the web material is passedthrough treating apparatus to dry or cure the treating material.Heretofore, it has not been possible, at least in commercialinstallations, to change the direction of travel of the web materialduring the treating operation since the treating material adhering tothe surface of the web is easily transferred to the surface of anymember coming in contact therewith, such as a direction-changing roller.In general, such transfer or offsetting is highly undesirable.

To dry or cure such treated material in a single pass, very high dryingtowers, often six or more stories in height, have been heretoforeemployed. After bathing or wetting both sides of the web material, theweb is directed vertically upward through a drying tower at a rate ofspeed calculated to fully cure or dry the treating material by the timethe treated portion of the web reaches the top of the drying tower. Atthat point directionchanging rollers reverse the travel of the web anddirect it vertically downward to a take-off roll.

In such a process, there is little or no drying or curing of thetreating substance during the downward pass. This results in wasted timeand, in most cases, wasted heat and, therefore, less elficientoperation. In addition, because of the required height of these dryingtowers, initial plant building and equipment investment is extremelyhigh and any reduction therein is exceptionally desirable.

In general, the objects of the present invention are accomplished bysupporting the treated Web material on a thin film of air to space itfrom a direction changing roller so that the treating material will notbe transferred to the roller. Apparatus intended to operate on thisprinciple has heretofore been proposed as shown, for example, by UnitedStates Patents Nos. 2,689,196, issued September 14, 1954, to l. S.Daniels for Web Drier; 3,057,079, issued Oct. 9, 1962, to A. G. M.Schmidt for Apparatus for Contactless Guiding and Conveyin of FlexibleSheet- Like Products; and 3,216,638, issued Nov. 9, 1965. to D. I.Brickle et al. for Air Cushion Method and Apparatus.

The novel direction changing apparatus invented by 3,3l3,4b2 PatentedApr. 11, 1967 applicant is of much simpler construction than theheretofore proposed devices disclosed in the foregoing patents and isaccordingly significantly cheaper to fabricate and to maintain.

Another important disadvantage of the devices disclosed in theabove-mentioned patents is that only a small percentage of the airsupplied to the device will flow through the portion of the devicearound which the supported web is trained. Therefore, these prior artdevices are incapable of actually providing a web supporting film of airexcept, perhaps, when impracticably high flows of air are employed. Inthe present invention, in contrast, a novel air supply port designpermits virtually all of the air supplied to the direction changingapparatus to be gainfully employed in forming a web-supporting air film.

In previously known devices of the same general type as disclosedherein, the air supply ports have been of uniform cross section or havehad a relatively large diameter inlet portion followed by a smalldiameter exit or outlet portion. The disadvantage of these holeconfigurations is that practically all of the air flows through theports which are not covered by the web trained around the air flotationdevice. Accordingly, these previously known devices can be made tooperate, if at all, only by supplying impracticably high volumes of airto them.

Apparatus similar in appearance to that invented by applicant is alsoshown in United States Patents Nos. 2,753,181 issued to D. R. Andrews etal. Oct. 13, 1959, for Web Reeling System; 2,954,911, issued to H. K.Baumeister et al. Oct. 4, 1960, for Tape Drive; and 2,968,- 702, issuedto I. P. Fay Jan. 17, 1961, for Transport Means for a MagnetRecorder-Reproducer. None of these patents, however, suggest that thedisclosed apparatus could be used to solve the problems in the heattreating of treated web materials discussed above. The Fay apparatus,for example, through it somewhat resembles applicants invention inappearance, operates in an entirely different manner and, operated asdisclosed by the inventor, would be entirely unsuitable for applicantspurposes. Thus, in the Pay patent, a perforated drum is employed as afeeding device for a recording tape by evacuating the hollow interior ofthe drum so that the tape will be forced by air pressure against itsouter surface to provide a frictional device connection between the drumand the tape. This apparatus would obviously be unsuitable for alteringthe direction of web material treated with an easily displaceabletreating material which it is desired to prevent from transferring tothe direction changim member.

In the Andrews patent a magnetic tape is supported from adirection-changing and guiding member on an air film. However, noutility is disclosed for the Andrews apparatus other than in thestabilizing or guiding of a magnetic tape, and the patent is directedalmost entirely to an arran ement of jets or nozzles for producing afiow pattern that will cause the tape to move to a centered position ifit tends to drift along the direction-changing and guiding member.

The purpose and function of the Baumeister et al. patent is even moreremote from applicants invention. This patent is much like the Paypatent in that it employs a perforated evacuated cylinder to drive amagnetic tape. While Baumeister et a1. do suggest employing a dynamicflow of air through a perforated cylinder to provide an air cushion,their reason for doing so is merely to permit the tape to move relativeto a direction-changing member. There is no suggestion in the Baumeisteret al. patent that such an air film could be employed for the purposesto which it has been adapted in the present invention.

Accordingly, it is an important object of the present invention toprovide novel improved methods and ap paratus for treating continuouswebs which have treating material on both sides of the web.

It is another object of the present invention to provide novel apparatusand methods for changing the direction of travel of a continuous webunder treatment while preventing transfer of the treating material tothe surface of the apparatus.

Another object of the present invention is to provide novel methods andapparatus for changing the direction of travel of a web material duringtreatment thereof by means spaced away from the web material.

Still a further specific object of the present invention is to provideair flotation means for changing the direction of the movement ofcontinuous webs having treating materials on both sides thereof by meansof a dynamic air flow adjacent the web at the direction'change locale tospace the web away from the flotation means on a film or cushion of airand thus prevent transfer of the treating material from the web to thedirection changing means.

It is still another object of the instant invention to provide apparatusfor treating sheet material which requires substantially less expensiveplant facilities than present commercial apparatus.

It is another object of the present invention to provide apparatus andmethods for treating sheet material which are faster and more ethcientthan present commercial practices,

These and other objectives and advantages of the invention will .beapparent to those conversant with the art from a reading of thefollowing description and subjoined claims in conjunction with theannexed drawings, in which:

FIGURE 1 is a schematic elevation of the method and apparatus of thepresent invention;

FIGURE 2 is an enlarged elevation, in section, of direction-changingmechanism employed in the apparatus of FIGURE 1;

FIGURE 3 is a plan view of the perforated surface of thedirection-changing apparatus of FIGURE 2;

FIGURE 4 is a fragmentary section showing one perforation of the outersurface of the direction-changing apparatus of FIGURE 2; and

FIGURE 5 is a sectional view showing a modified direction-changingapparatus.

FIGURE 1 shows one embodiment of the present invention in the form of amodified tower drier 6, having two passes instead of one andsubstantially one-half the height of tower driers in commercial use. Astandard roll of untreated sheet material 8 is spirally mounted on amandrel 10 and the combination is rotated unitarily, causing web 12 totravel in the direction of arrow 14. Web 12 may be any standard sheetmaterial including paper, fabric, sheet metal strip, etc. In theembodiment of FIGURE 1, web 12 is directed over roller 16 at station 17into tank 18, immersed in treating material 20, directed about rollers22 and 24, respectively, and thereafter moved vertically upward out oftank 18. Station 17 typifies one of several types of treatmentapparatus. Coating, dusting, inking, distribution station, etc. areequivalents. Furthermore, station 17 need not necessarily be located ina horizontal attitude, as the invention also encompasses vertical ordiagonally oriented stations.

Web 12 is directed away from station 17 as shown by arrow 26 in FIGURE 1through rollers 28 and into the upward pass 30 of tower drier 6 betweenseries heaters 32 and 34. Satisfactory series heaters are disclosed inthe co-pending application of Horace L. Smith, Ir., Ser. No. 64,965,filed Oct. 25, 1960 (now Patent No. 3,174,228), although other types ofheaters may, of course, be employed. Web 12 exits from upward pass 39 attangent point 36 and thereafter moves in the direction of arrow 38 totangent point 40, In contrast to the prior art driers in which thetreated material is dry when it reaches the upper end of the drier, thetreating material adhering to web 12 at tangent point 36 in drier 6 isonly partially cured or dried because of the reduced drier height and isreadily transferable to any solid coming in contact therewith.

Heretofore, changes in direction of travel of partially treated sheetmaterial was avoided by providing extremely high tower driersfacilitating complete treatment during upward travel, and substantiallyno additional treatment during downward travel of the web.Direction-changing mechanism 42 obviates the need for such extendedvertical tower driers, allowing treatment during both upward anddownward travel by providing a compressed air chamber 44 which emitscompressed air through perforations in cylinder wall 46 to space bend 48of web 12 away from direction-changing mechanism 42 on an air film 5t).

Thereafter web 12 proceeds vertically downward from tangent point 49through drier pass 52 between series heaters 54 and 56, similar toseries heaters 32 and 34, to complete the treatment of the materialadhering to web 12. Subsequently web 12 passes underneath roller 58 inthe direction of arrow 61) and is wrapped on mandrel 62 to form a rollof treated material 64.

Direction-changing mechanism 42, best shown in FIG- URE 2, comprises adrum 45 having a cylindrical wall 46 and closed at each end by end wall47. Appropriate drive means (not shown) are provided for rotating drum45 on axles 69 about axis of rotation 70 in the direction of arrow 72which is parallel to the direction of travel of web 12 as shown :byarrow 38 (rotation of the websupporting device is most important in highspeed operations as shearing of the air film by the web and theresulting decrease in efiectiveness can be minimized by so rotating thedrum that its surface speed matches the web speed).

Web 12 is spaced from cylindrical wall 46 by air film 5% along the 180angle of curvature shown by line 73. Cylindrical wall 46, in conjunctionwith its end walls 47, forms a compressed air chamber 44 which receivesair under pressure from a suitable source of compressed air (not shown)in any appropriate fashion such as through the passage 69a in axle 69.The source of compressed air and passage 6% form a system for forcingairfrom chamber 44 to the exterior of cylindrical wall 46, the air flowingto the exterior of wall 46 through perforations or ports 74, which arebest shown in FIGURE 3. Air from perforations 74 pressure-bears againstweb 12 along the 180 angle of curvature indicated by line 73.

For reasons of economy, it is desirable to prevent air flow through theperforations 74 which are not immediately adjacent web 12 at bend 48.Therefore, a shoe member 76 is provided to seal 01f the perforations 74not adjacent bend 43 of web 12. Shoe member 76 (FIGURE 2) includes, ateach end of drum 45, a tubular member 78, journalled on a drum-suportingaxle 69 and concentrically located about axis of rotation 70, and hangermembers 80 and 82. The two sets of hanger members gravitatingly hold ashield 84 in sealing engagement against cylindrical wall 46 ofdirection-changing mechanism 42 by seal means 86 and 88 extendinglongitudinally of cylindrical wall 46 and by end seals (not shown).

Referring to FIGURE 3, additional perforations 74 (not shown), outwardlyadjacent rows of perforations 9t) and 92 along edges 94 and 96 of drum45, respectively, may be required in certain manifestations of thepresent invention to compensate for pressure drop at the edge of web 12and/ or to accommodate lateral shifting of web 12 to maintain thelongitudinal edges of web 12 away from cylindrical wall 46.

An enlarged fragmentary cross-section of cylindrical wall 46 showing oneof a series of relatively large apertures, perforation or ports 74, isshown in FIGURE 4. A tubular orifice or nozzle block 1% is recessedlyinserted into perforation 74 so that an equal amount of compressed airis discharged from each perforation 74, resulting in equal pressuredistribution across web 12 at bend 48. Compressed air flowing intoperforation 74, shown by arrows 101 and 102, engages convergent surface104 of the nozzle 105 in nozzle block 100 (which is the inlet section ofperforation or port 7 4) travels through nozzle passage 106, and outoutlet or exit section 108 to thereafter pressure-bear against web 12.This movement of air causes considerable pressure drop through theorifice or nozzle 105, achieving equal distribution of air pressureacross the entire surface of web 12 along arrowed line 73 (FIGURE 2).

Air flowing out of perforation 74, shown by arrows 112 and 114, embracesweb 12 (usually substantially fluid impervious) to space web 12 awayfrom cylindrical wall 46 by dynamic air flow film 110. It is criticalthat dynamic air fiow film 110 receive a continuous flow of air undersubstantially uniform pressure from perforations 74; mere staticdifferences in pressure are inadequate for the present invention.

The air flow necessary to provide a web supporting film is sharplyreduced from that required in prior art devices by the novel ports ofthe present invention, which have a small diameter nozzlelike inletsection followed by a large diameter exit section or cavity. In thisnovel arran ement, the inlet nozzle sections meter or limit the fiow ofair through the uncovered ports so that air does not escape through themat a significantly higher rate than it does through the ports covered bythe web. Accordingly, in the present invention, there is no large escapeof air through the uncovered ports as in previously known devices.

At the same time the enlarged exit cavities make the pressure dropthrough the covered and uncovered ports much more nearly equal than itis in the prior art devices in which straight sided apertures areemployed. Consequently, there is less tendency for the air exitingthrough the covered ports to escape from beneath the web to thesurrounding atmosphere, any flow of this nature being at a low velocity.Consequently, in the present invention, there is a still furtherreduction in air flow requirements and the formation of a more stableweb supporting air film than is provided by prior art devices.

The ratio of the diameters of the inlet and outlet sections of the portsin the present invention may vary from application to application. Inone typical application, however, inlet section 106 has a diameter and across sectional area of 0.02 sq. in. Outlet section 108 has a 1.25"diameter and a cross section diameter of 1.00 sq. in. By using this portarrangement, the flow of air flow through the uncovered ports wasreduced to one thirtyseventh of what there would have been if ports witha one square inch cross section and either of the previously known portconstructions discussed above were employed. This provides a substantialoverall reduction in the power of the blower necessary and acorresponding decrease in equipment and operating costs.

The pressure of the dynamic air film 50 between web 12 and cylindricalwall 46 required to support the web is, in theory, numerically equal tothe tension in web 12, due to its own weight, divided by the surfacearea of web 12 between tangent points 36 and 40, designated by line 73.For example, assuming the unit weight of web 12 to be pound per squarefoot which is pound per inch of web width, the vertical run (i.e., thelength of web 12 between station 17 and roller 58) to be 30 feet, andthe width of web 12 to be 120 inches, the resulting tension in web 12due to its own weight would be aproximately 60 pounds or 0.3 pound/inchof width. The surface bearing area at bend 48 divided into 60 poundstension requires an air pressure of approximately 0.05 pound per squareinch to support web 12, which requires an air flow at a velocity of1,300 ft. per minute.

Assuming that drum 45 is 10 feet long and 10 inches in diameter, thetotal length of escape area for air cushion 50 (assuming also a changeof direction) would be approximately 23 feet. Moreover, assuming airfilm 50 to be 0.01 of an inch thick, the total air escape area would be0.025 square feet. Using a velocity flow of 2000 ft. per minute, toprovide a safety margin, the total volume of air would only be 50 cubicft. per minute, which is nominal.

In actual practice an air velocity on the order of 4000 feet per minutewould be used in an installation with the operating parameters assumedabove. The reason for this is that, to insure proper operation of thedirectionchanging mechanism, the flow between those perforations covered-by web 12 and those that are exposed should be substantially equalizedto provide an equal pressure distribution across the span of thedirection changing mechanisrn. The difference in flow between thecovered and exposed perforations can be reduced to an inconsequentialmagnitude by maintaining a materially higher pressure in air chamber 44than in the annular region between direction-changing mechanism 42 andweb 12 in addition to employing the novel port configuration describedabove. This may be done by increasing the flow velocity (which varieswith the square of the differential of the pressure on opposite sides ofthe perforations) to provide a higher pressure differential between theinterior and exterior of the direction changing mechanism.

For example, by doubling the calculated flow velocity of 1300 feet perminute and sizing and spacing the perforations to limit the total flowto that sufiicient to provide a pressure of 0.05 p.s.i. under the web, apressure of 0.20 p.s.i. can be maintained in air chamber 44. Tocompensate for leakage and other practical factors requiring minorcorrections, the pressure in air chamber 44 would preferably bemaintained at 0.5 p.s.i. in actual practice so that the flow velocitywould be 4000 feet per minute and the pres-sure differential across theperforations would be 0.45 p.s.i.

Under these conditions the flow through the covered and uncoveredperforations would be so nearly equal that the small difference in flowcould be disregarded.

Direction-changing mechanism 42, appearing in FIG- URES 1-4, is only onemanifestation of the present invention for changing the direction oftravel of a partially treated substance adhering to web 12. FIGURE 5shows a second manifestation, stationary direction-changing mechanism120, which includes a drum structure 121 unitarily formed of asemi-cylindrical wall 122, base walls 124 and 126, tubular air inletmember 128, and end walls (not shown). The direction of travel of web12, having partially treated substance adhering thereto, is changed bycompressed air proceeding into chamber 130, out perforations 132,preferably of the type discussed above, to pressure-bear against Web 1 2and space it from cylindrical wall 122 by air cushion 134 in the mannerdescribed previously in conjunction with the embodiment of FIGURE 1.Consequently, no solid material touches the material adhering to web 12while the traveling direction of web 12 is selectively changed.

While only two manifestations of the present directionchanging mechanismhave been shown, namely, directionchanging mechanisms 42 and 120, othertypes of dynamic air fiow pressure-bearing mechanisms are comprehendedby this invention employing the principles discussed above.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription.

What is claimed and desired to be secured by Letters Patent is:

1. Apparatus for changing the direction of travel of a web duringprocessing thereof in which the web is supported on a film of air,comprising:

(a) a single hollow drum having a wall of substantial thickness, saiddrum being rotatably supportable and being adapted to have the webtrained thereover; and

(b) ports through said wall providing communication between the interiorand exterior of the drum, Whereby air may be forced from the interior ofsaid drum to the exterior thereof to provide a filrnlike cushion of airbetween the drum and the web, said ports each having an inlet section ofrelatively small crosssectional area for metering the flow of airthrough the ports and an outlet section communicating with said inletsection, said outlet section having a substantially largercross-sectional area than the inlet section; and

(c) means for sealing off the perforations through the portion of thedrum other than those over Which the web is trained comprising:

(1) an arcuate shield member within said drum cooperating with the innersurface thereof; (2) support means mounting said shield for freerotational movement about an axis coincident with the axis of rotationof said drum, and

(3) seal means extending along opposite edges of said shield anddisposed between said shield and said drum for preventing escape of airthrough perforations underlying the shield.

2. The apparatus of claim 1, wherein the inlet sections of said portsare formed in nozzle blocks disposed in apertures through the wall ofsaid structure, the outlet sections of said ports being provided by saidapertures.

References Cited by the Examiner UNITED STATES PATENTS 2,717,710 9/1955Baker et a1 22695 X 3,075,679 1/1963 VVadey 22697 X 3,097,778 7/1963Pendleton 226-97 X 3,142,428 7/1964 Faeber 22695 3,151,795 10/1964Gwillim 22695 M. HENSON WOOD, JR., Primary Examiner.

ALLEN N. KNOWLES, Examiner.

1. APPARATUS FOR CHANGING THE DIRECTION OF TRAVEL OF A WEB DURINGPROCESSING THEREOF IN WHICH THE WEB IS SUPPORTED ON A FILM OF AIR,COMPRISING: (A) A SINGLE HOLLOW DRUM HAVING A WALL OF SUBSTANTIALTHICKNESS, SAID DRUM BEING ROTATABLY SUPPORTABLE AND BEING ADAPTED TOHAVE THE WEB TRAINED THEREOVER; AND (B) PORTS THROUGH SAID WALLPROVIDING COMMUNICATION BETWEEN THE INTERIOR AND EXTERIOR OF THE DRUM,WHEREBY AIR MAY BE FORCED FROM THE INTERIOR OF SAID DRUM TO THE EXTERIORTHEREOF TO PROVIDE A FILMLIKE CUSHION OF AIR BETWEEN THE DRUM AND THEWEB, SAID PORTS EACH HAVING AN INLET SECTION OF RELATIVELY SMALLCROSSSECTIONAL AREA FOR METERING THE FLOW OF AIR THROUGH THE PORTS ANDAN OUTLET SECTION COMMUNICATING WITH SAID INLET SECTION, SAID OUTLETSECTION HAVING A SUBSTANTIALLY LARGER CROSS-SECTIONAL AREA THAN THEINLET SECTION; AND (C) MEANS FOR SEALING OFF THE PERFORATIONS THROUGHTHE PORTION OF THE DRUM OTHER THAN THOSE OVER WHICH THE WEB IS TRAINEDCOMPRISING: (1) AN ARCUATE SHIELD MEMBER WITHIN SAID DRUM COOPERATINGWITH THE INNER SURFACE THEREOF; (2) SUPPORT MEANS MOUNTING SAID SHIELDFOR FREE ROTATIONAL MOVEMENT ABOUT AN AXIS COINCIDENT WITH THE AXIS OFROTATION OF SAID DRUM, AND (3) SEAL MEANS EXTENDING ALONG OPPOSITE EDGESOF SAID SHIELD AND DISPOSED BETWEEN SAID SHIELD AND SAID DRUM FORPREVENTING ESCAPE OF AIR THROUGH PERFORATIONS UNDERLYING THE SHIELD.